My friend and writer David Sims recommended an interview of Louis Markos about finding and writing great sentences. Markos says the following about the difference between a good and a great sentence:

A good sentence conveys its meaning in a clear and balanced way. The sentence becomes great when it takes on a life of its own-when you enjoy reading it, not just for what it teaches you, but for its sound and its tone and its music. A great sentence should be savored like a gourmet meal or like a piece of fine music.

-Louis Markos in an interview by John Starke for The Gospel Coalition Reviews.

Read the whole interview here.